The overall objective of the proposed research is to define the age dependent changes in elastin and collage composition, specifically the transition in the ratios of microfibrillar to amorphous elastin and type 1 to type 111 collagen. The microfibrillar component of elastin will be isolated from parenchymatous human tissues of different age groups, especially lung, and from skin and lung of old (2-3 year) and young mice. Relative yields will be compared, amino acid and carbohydrate analyses performed and special stains used to localize and quantitate the microfibrillar and the amorphous moiety by electronmicroscopy. Identify with the microfibrillar component of fetal tissues will also be tested by immunochemical procedures. Collagen 111 will be isolated after pepsin digestion and the alpha type 111 chains separated from the type 1 alpha-1 and alpha-2 chains by CM cellulose column chromatography. The observed compositional changes in elastin and collagen of the same tissue during normal aging will be correlated.